Method and apparatus for assigning response channel resources

ABSTRACT

An apparatus and method for assigning an acknowledgement (ACK)/a negative acknowledgement (NACK) channel resources. The method includes setting a User Equipment (UE) to feed back Acknowledgement (ACK)/Negative Acknowledgement (NACK) information in a Carrier Aggregation (CA) mode; setting a Transmit Power Control (TPC) field of a Physical Downlink Controlling Channel (PDCCH) message to transmit an ACK/NACK Resource Indicator (ARI) information, when a Downlink Assigning Indicator (DAI) value of the PDCCH message of a Secondary cell (Scell) scheduled in a non cross-carrier manner is 1; setting the TPC field to transmit a TPC command for the ACK/NACK feedback information, when the DAI value is greater than 1; and transmitting the PDCCH message and downlink data to the UE.

PRIORITY

This application claims priority under 35 U.S.C. §119(a) to ChinesePatent Application No. 201110037720.1, which was filed in the StateIntellectual Property Office on Feb. 12, 2011, the entire content ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to wireless communicationtechnology, and more particularly, to a method and an apparatus forassigning response channel resources.

BACKGROUND ART

A Long Term Evolution (LTE) system is based on Hybrid Automatic RepeatreQuest (HARQ) for data transmission. More specifically, based on datareception status, the data receiver in an LTE system will send receivingstatus feedback information, i.e., an ACKnowledgement (ACK) or aNegative ACKnowledgement (NACK). Scheduling information of dynamicdownlink data is transmitted through a Physical Downlink Control CHannel(PDCCH), while for a Semi-Persistent Scheduling (SPS) service, becausethe scheduling information is sent through the PDCCH when the downlinkdata is retransmitted, it is not necessary to send PDCCH information ininitial transmission scheduling information of the downlink data.

In an LTE Time Division Duplex (TDD) system, Downlink AssigningIndication (DAI) technology allows a User Equipment (UE) to determinewhether PDCCH information sent by a Node B is lost or not. Specially, aDAI identifies PDCCH information of a next downlink sub-frame of acurrent bundling window. For example, 2 bits in a DAI field can indicate4 values, easily identifying the PDCCH information when a size of abundling window (M) is 1, 2, 3, or 4. However, when TDD configurationfor uplink and downlink is 5, then M is 9. Accordingly, the 4 values ofthe DAI field need to be re-used. For example, when the number of acurrent PDCCH is a, its DAI value is obtained by modulo operation with4, as shown in Equation (1).mod(a−1,4)+1  (1)

In an LTE-Advanced (LTE-A) system, Carrier Aggregation (CA) technologyis used to support higher transmission rates, i.e., at least threeComponent Carriers (CC) are aggregated to provide a larger workbandwidth. Based on the CA, a Node B sends downlink data to a UE usingthe at least three CCs. Accordingly, the UE provides ACK/NACK feedbackinformation for downlink data of at least three CCs. Herein, each CC isreferred to as a “cell”.

According to current discussion for LTE-A, up to 4-bit ACK/NACKtransmission is supported, based on channel selection technology. Morespecifically, a Frequency Division Duplex (FDD) system uses a 4-bitmapping table as shown in Table 1 below. In Table 1, ACK/NACK channels 1and 2 correspond to two ACK/NACK bits of a Primary cell (Pcell), andACK/NACK channels 3 and 4 correspond to two ACK/NACK bits of a Secondarycell (Scell). In Table 1, N means NACK, A means ACK, and D meansDiscontinuous Transmission (DTX). In Table 1, the feature is used thatthe two ACK/NACK channels of the same cell are always available orunavailable, thus the feedback performance and power controlling areoptimized.

TABLE 1 ACK/NACK channel Pcell Scell 1 2 3 4 A, A A, A −1 A, N A, A −jN, A A, A −j N, N A, A −1 A, A A, N j A, N A, N 1 N, A A, N 1 N, N A, Nj A, A N, A −1 A, N N, A j N, A N, A −j N, N N, A 1 A, A N, N −1 A, N N,N j N, A N, N −j N, N N, N 1 A, A D, D −1 A, N D, D j N, A D, D −j N, ND, D 1 D, D A, A −1 D, D A, N j D, D N, A 1 D, D N, N No transmission D,D D, D No transmission

Another example of a 4-bit mapping table is shown in Table 2 below. InTable 2, a corresponding ACK/NACK channel is selected for transmissiononly when a certain piece of ACK/NACK information is an ACK. There is anexception, in that in order to fully use feedback capability of the M (Mis 2, 3, or 4) channels, when a first piece of ACK/NACK information is aNACK and other pieces of ACK/NACK information are NACK or DTX, aQuadrature phase-shift keying (QPSK) constellation point of the firstchannel can function as an indication. Table 2 is used when the 4ACK/NACK bits and their corresponding ACK/NACK channels are separated.

TABLE 2 ACK/ QPSK ACK/NACK information NACK constellation b0 b1 b2 b3channel point D N/D N/D N/D DTX N N/D N/D N/D h0 1 A N/D N/D N/D h0 −1N/D A N/D N/D h1 −j A A N/D N/D h1 j N/D N/D A N/D h2 1 A N/D A N/D h2 jN/D A A N/D h2 −j A A A N/D h2 −1 N/D N/D N/D A h3 1 A N/D N/D A h0 −jN/D A N/D A h3 j A A N/D A h0 j N/D N/D A A h3 −j A N/D A A h3 −1 N/D AA A h1 1 A A A A h1 −1

A method for ACK/NACK information feedback in an LTE-A TDD system basedon channel selection is currently being discussed, which is based on theabove-described DAI design of LTE. First, the ACK/NACK informationcorresponding to each PDCCH is sorted in ascending order according tothe DAI. If there is an SPS service in the PDCCH, its ACK/NACKinformation is given priority. Thereafter, a number of consecutive ACKsstarting from first ACK/NACK information is fed back to each cell.

More specifically, when the size of the bundling window M is 3, thereare 4 possible values for the number of consecutive ACKs of each cell,that is, 0, 1, 2, or 3. Accordingly, these four values can be mapped to2 bits, as the example shown in Table 3 below. When the size of thebundling window M is 4, there are 5 possible values for the number ofconsecutive ACKs of each cell, i.e., 0, 1, 2, 3, or 4. Here, these fivevalues could be transferred to 4 states to be mapped to 2 bits. One ofthe transferring methods is shown in Table 4 below. In Table 4, N meansNACK, A means ACK, D means DTX, and the symbol “/” means “or”.

TABLE 3 3 pieces of ACK/NACK information at most in the bundling windowMapping states A, A, A A, A A, A, N/D N/D, A A, N/D, any A, N/D N, any,any N, N/D D, any, any D, N/D

TABLE 4 4 pieces of ACK/NACK information at most in the bundling windowMapping states A, A, A, N/D A, A A, A, N/D, any N/D, A A, A, A, A A, N/DOr, A, D, D, D N, any, any, any N, N/D or, A, N/D, any, any except A, D,D, D D, any, any, any D, N/D

According to the mapping states in Tables 3 and 4, 2-bit Pcellinformation and 2-bit Scell information are obtained, and ACK/NACKinformation could be fed back using the channel selection methodaccording to the mapping of Table 1 or 2.

Allocating 4 candidate ACK/NACK channels for feeding back 4 bitsinformation to support channel selection is also under discussion.

More specifically, for the ACK/NACK channel corresponding to the 2 bitsof a Pcell, when there is SPS service, the first ACK/NACK channel is asemi-static configured ACK/NACK channel for SPS service, and the secondACK/NACK channel is determined by the PDCCH scheduling a Pcell with itsDAI of 1. For example, if a minimum Control Channel Element (CCE) indexof a PDCCH is n, one ACK/NACK channel could be mapped with the LTEmethod according to the CCE index n. When there is no SPS service, thetwo ACK/NACK channels are determined sequentially by PDCCHs of twoPcells with their DAIs of 1 and 2, respectively. For example, if theminimum CCE index of the PDCCH with its DAI value of 1 is n1 and theminimum CCE index of the PDCCH with its DAI value of 2 is n2, then thefirst ACK/NACK channel can be mapped with LTE method according to theCCE index n1, and one ACK/NACK channel can be mapped with LTE methodaccording to the CCE index n2.

For the ACK/NACK channel corresponding to the 2 bits of an Scell, whencross-cell scheduling is used, the two ACK/NACK channels aresequentially determined by PDCCHs of two Pcells with their DAIs of 1 and2, respectively. For example, if the minimum CCE index of the PDCCH withits DAI value of 1 is n1 and the minimum CCE index of the PDCCH with itsDAI value of 2 is n2, then the first ACK/NACK channel can be mapped withthe LTE method according to the CCE index n1, and the second ACK/NACKchannel can be mapped with LTE method according to the CCE index n2.When no cross-cell scheduling is used, the two ACK/NACK channels areconfigured by a higher layer, and the ACK/NACK Resource Indicatinginformation (ARI) in the PDCCH scheduling Scell is used to improveassigning flexibility.

According to the current LTE-A discussions, a power controlling commandis still sent in a Transmit Power Control (TPC) field of the PDCCHscheduling Pcell, to ensure the Node B to control transmitting power ofthe UE. For the Scell using cross-carrier scheduling, a powercontrolling command is still sent in a TPC field of PDCCH schedulingScell. For an Scell using non cross-carrier scheduling, a TPC field ofPDCCH scheduling Scell is redefined as an ARI for indicating ACK/NACKchannel resources, which means that the power controlling informationcannot be carried in the TPC field. Accordingly, if the UE does notreceive a PDCCH of a Pcell correctly, or the Node B does not currentlyschedule dynamic data in the Pcell, the UE will not receive the powercontrolling command, negatively affecting the reliability of ACK/NACKfeedback information sent upstream.

SUMMARY OF THE INVENTION

Accordingly, the present invention is designed to address at least theproblems and/or disadvantages described above and to provide at leastthe advantages described below.

Accordingly, an aspect of the present invention is to provide a methodfor assigning ACK/NACK channel resources, which improve the powercontrolling performance of uplink signal, while indicating the assignedACK/NACK channel.

In accordance with an aspect of the present invention, a method isprovided for allocating response channel resources by a Node B in awireless communication system. The method includes setting a UserEquipment (UE) to feed back Acknowledgement (ACK)/NegativeAcknowledgement (NACK) information in a Carrier Aggregation (CA) mode;setting a Transmit Power Control (TPC) field of a Physical DownlinkControlling Channel (PDCCH) message to transmit an ACK/NACK ResourceIndicator (ARI) information, when a Downlink Assigning Indicator (DAI)value of the PDCCH message of a Secondary cell (Scell) scheduled in anon cross-carrier manner is 1; setting the TPC field to transmit a TPCcommand for the ACK/NACK feedback information, when the DAI value isgreater than 1; and transmitting the PDCCH message and downlink data tothe UE.

In accordance with another aspect of the present invention, a method isprovided for using response channel resources by a User Equipment (UE)in a wireless communication system. The method includes receiving aPhysical Downlink Controlling Channel (PDCCH) message and downlink datafrom a Node B; generating ACK/NACK feedback information for the downlinkdata; determining an ACK/NACK channel corresponding to a Secondary cell(Scell) based on the PDCCH message scheduling the Scell with a DAI valueof 1, and determining a transmitting power of the ACK/NACK feedbackinformation based on the PDCCH message scheduling the Scell with a DAIvalue of greater than 1, when the Scell is scheduled in a noncross-carrier manner; and transmitting the ACK/NACK feedback informationwith the determined transmitting power using the determined ACK/NACKchannel.

In accordance with another aspect of the present invention, a Node B isprovided for allocating response channel resources in a wirelesscommunication system. The Node B includes a setting unit for setting aUser Equipment (UE) to feed back Acknowledgement (ACK)/NegativeAcknowledgement (NACK) information in a Carrier Aggregation (CA) mode,setting a Transmit Power Control (TPC) field of a Physical DownlinkControlling Channel (PDCCH) message to transmit an ACK/NACK ResourceIndicator (ARI) information, when a Downlink Assigning Indicator (DAI)value of the PDCCH message of a Secondary cell (Scell) scheduled in anon cross-carrier manner is 1, and setting the TPC field to transmit aTPC command for the ACK/NACK feedback information, when the DAI value isgreater than 1; and a transmitter for transmitting the PDCCH message anddownlink data to the UE.

In accordance with another aspect of the present invention, a UserEquipment (UE) is provided that uses response channel resources in awireless communication system. The UE includes a receiver for receivinga Physical Downlink Controlling Channel (PDCCH) message and downlinkdata from a Node B; a generator for generating ACK/NACK feedbackinformation for the downlink data, and determining an ACK/NACK channelcorresponding to a Secondary cell (Scell) based on the PDCCH messagescheduling the Scell with a DAI value of 1, and determining atransmitting power of the ACK/NACK feedback information based on thePDCCH message scheduling the Scell with a DAI value of greater than 1,when the Scell is scheduled in a non cross-carrier manner; and atransmitter for transmitting the ACK/NACK feedback information with thedetermined transmitting power using the determined ACK/NACK channel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present invention will be more apparent from thefollowing detailed description when taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a flowchart illustrating a method for assigning ACK/NACKchannel resources according to an embodiment of the present invention;

FIG. 2 illustrates a TPC field in a PDCCH for scheduling an Scell fornon-cross carrier scheduling according to an embodiment of the presentinvention;

FIG. 3 is a flowchart illustrating eNB procedures for a TPCconfiguration according to an embodiment of the present invention;

FIG. 4 is a flowchart illustrating UE procedures for TPC and UL resourceallocation according to an embodiment of the present invention;

FIG. 5 is a block diagram illustrating a Node B apparatus for allocatingACK/NACK channel resources according to an embodiment of the presentinvention; and

FIG. 6 is a block diagram illustrating a UE apparatus that usesallocated ACK/NACK channel resources according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention will now be described indetail with reference to the accompanying drawings. In the followingdescription, specific details such as detailed configuration andcomponents are merely provided to assist the overall understanding ofthese embodiments of the present invention. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein can be made withoutdeparting from the scope and spirit of the present invention. Inaddition, descriptions of well-known functions and constructions areomitted for clarity and conciseness.

In accordance with an embodiment of the present invention, a method ofallocating response channel resources, e.g., ACK/NACK channel resources,is provided.

FIG. 1 is a flowchart illustrating a method for assigning ACK/NACKchannel resources according to an embodiment of the present invention.

Referring to FIG. 1, there are two modes of feeding back ACK/NACKinformation for a UE configured to be in the CA mode in LTE: (1)separately feeding back ACK/NACK information of each sub-frame on eachcell in a bundling window, in which the ACK/NACK information istransmitted based on Physical Uplink Control Channel (PUCCH) format 3;and (2) binding the ACK/NACK information in the bundling window on eachcell to reduce the feedback overhead, in which the ACK/NACK informationis transmitted based on PUCCH format 3, or based on the channelselection. FIG. 1 will be described below, in which the ACK/NACKinformation is transmitted based on the channel selection, i.e., thesecond mode.

The ARI processing of FIG. 1 also fits to the situation that ACK/NACKinformation is transmitted based PUCCH format 3.

Referring to FIG. 1, in step 100, according to a factor of the channelstatus of the UE or of the service requirement, the Node B configuresthat the ACK/NACK feedback mode the UE uses in the CA mode is based onchannel selection using Radio Resource Control (RRC) signalling.

In step 101, a Node B scheduler assigns downlink channel resources on aPcell and an Scell for the UE in the CA mode, and sends PDCCHinformation and corresponding dynamic data or sends service data of SPS.More specifically, the Node B puts DAI information in each piece ofPDCCH information using the DAI method defined in LTE, which indicatesthe number of PDCCH sent by the Node B in the bundling window up to thecurrent sub-frame. When the size of the bundling window is 9, the numberof PDCCH is modelled by 4. When M is 2, 3, or 4, the DAI actsessentially as a counter for counting the number of PDCCHs from 1.

In accordance with an embodiment of the present invention, the TPC fieldin PDCCH scheduling Pcell carries a TPC command when the Node B sendsPDCCH information, and when Scell is scheduled in a cross-carriermanner, the TPC field in a PDCCH scheduling an Scell also carries a TPCcommand. When the Scell is scheduled in a non cross-carrier manner, theTPC field in a PDCCH scheduling an Scell with a DAI of 1 is redefined asan ARI, while the TPC field in a PDCCH scheduling an Scell with a DAI ofmore than 1 still carries a TPC command.

In step 102, the UE receives PDCCH information sent by the Node B, andcorresponding dynamic downlink data. Thereafter, the UE generatesACK/NACK feedback information.

Specially, when the Node B sends the downlink data with Multi InputMulti Output (MIMO), one bit of the 2-bit ACK/NACK information of asub-frame is determined with spatial bundling. Using spatial bundling,the ACK/NACK information is bound as ACK when both of the two bits areACKs; otherwise, the ACK/NACK information is bound as NACK. Thereafter,ACK/NACK information corresponding to each of the PDCCH channels feedingback ACK/NACK information is sorted in ascending order. If there is anSPS service in the PDCCH, its ACK/NACK information is given priority.Four feedback states are generated for each cell, which are mapped to2-bit ACK/NACK information. Here, it is assumed that each feedback staterepresents the number of consecutive ACKs from the first ACK/NACKinformation, e.g., using the methods shown in Table 3 and Table 4.

In step 103, the UE determines candidate channels to perform channelselection.

More specifically, for an ACK/NACK channel corresponding to 2 bits of aPcell, when there is an SPS service, the first ACK/NACK channel is asemi-static configured ACK/NACK channel for the SPS service, and thesecond ACK/NACK channel is determined by a PDCCH scheduling a Pcell withits DAI of 1. For example, if a minimum CCE index of a PDCCH is n, anACK/NACK channel can be mapped with an LTE method according to the CCEindex n.

When there is no SPS service, the two ACK/NACK channels are sequentiallydetermined by PDCCHs of two Pcells with DAIs of 1 and 2, respectively.For example, if the minimum CCE index of the PDCCH with its DAI value of1 is n1 and the minimum CCE index of the PDCCH with its DAI value of 2is n2, then the first ACK/NACK channel can be mapped with the LTE methodaccording to the CCE index n1, and the second ACK/NACK channel could bemapped with LTE method according to the CCE index n2.

For the ACK/NACK channel corresponding to the 2 bits of an Scell, whencross-cell scheduling is used, the two ACK/NACK channels aresequentially determined by PDCCHs of two Pcells with DAIs of 1 and 2,respectively. For example, if the minimum CCE index of the PDCCH with aDAI value of 1 is n1 and the minimum CCE index of the PDCCH with a DAIvalue of 2 is n2, then the first ACK/NACK channel can be mapped with theLTE method according to the CCE index n1, and one ACK/NACK channel couldbe mapped with the LTE method according to the CCE index n2.

When no cross-cell scheduling is used, the two ACK/NACK channels areconfigured by a higher layer, and ARI information in a PDCCH schedulingan Scell and with a DAI of 1 is used to indicate the two ACK/NACKchannels.

For an Scell scheduled with an uncross-cell, according to the method offeeding back the number of consecutive ACKs from the first piece ofACK/NACK information of step 102, when the number of consecutive ACKs isno less than 1, the UE receives the PDCCH with a DAI of 1. Thereafter,according to the setting method in step 101, the UE can receive twocandidate ACK/NACK channels with ARI information from the redefined TPCfield in this PDCCH. When the first piece of ACK/NACK information isDTX, i.e., the Node B sent a PDCCH with a DAI of 1, but the UE has notdetected this PDCCH correctly, then the UE has no available ARIinformation. However, because the design of channel selection mappingtable ensures that there is no possibility to choose candidate ACK/NACKchannels corresponding to an Scell in this situation, sending uplinkACK/NACK feedback information is not affected.

In step 104, the UE determines transmitting power when ACK/NACK signalis sent in the uplink direction, based on a received TPC command. Forexample, the transmitting power of the uplink controlling channel can bedetermined as shown in Equation (2).P _(PUCCH)(i)=g(i)+P _(others∘)  (2)

In Equation (2), g(i) represents the transmitting power adjusting valuein the uplink sub-frame i, which is determined based on the TPC command,and P_(others) represents other information for determining thetransmitting power.

When the transmitting power of the uplink controlling channel isdetermined in an accumulation manner, the transmitting power adjustingvalue g(i) can be determined using Equation (3).

$\begin{matrix}{{g(i)} = {{g\left( {i - 1} \right)} + {\sum\limits_{k_{m} = 0}^{M - 1}{\delta_{PUCCH}\left( {i - k_{m}} \right)}}}} & (3)\end{matrix}$

Alternatively, when the transmitting power of the uplink controllingchannel is not determined in an accumulation manner, the transmittingpower adjusting value g(i) can be determined using Equation (4).

$\begin{matrix}{{g(i)} = {\sum\limits_{k_{m} = 0}^{M - 1}{\delta_{PUCCH}\left( {i - k_{m}} \right)}}} & (4)\end{matrix}$

In Equations (3) and (4), M is the size of the bundling window,δ_(PUCCH)(i−k_(m)) is the transmitting power controlling value indicatedby the TPC command sent by the PDCCH in the downlink sub-frame i−k_(m),and k_(m) refers to each downlink sub-frame transmitted in a same uplinksub-frame. According to this definition, g(i) in the uplink sub-frame iequals the sum of the transmitting power adjusting value in thesub-frame i−1 and transmitting power controlling values of all thePDCCHs sent in the downlink bundling window corresponding to the uplinksub-frame.

In accordance with an embodiment of the present invention, when both ofthe two cells in the same downlink sub-frame send power controllingcommands, these two power controlling commands repeatedly indicate thesame value, and the reliability of the TPC command is enhanced. That is,if the UE does not detect the PDCCH on one of the cells, it can stillreceive the transmitting power controlling value of this sub-frame formthe TPC field of the PDCCH of another cell. Thereafter, a sum of the TPCfield values of PDCCHs are separately sent in each downlink sub-frame inthe bundling window corresponding to an uplink sub-frame. Alternatively,the TPC field values of PDCCHs sent in each downlink sub-frame in thebundling window corresponding to a uplink sub-frame separately indicatethe transmitting power controlling value of this uplink sub-frame. Thatis, all of the TPC fields of PDCCHs can repeatedly indicate a samevalue. Accordingly, when the UE receives a PDCCH, the UE will receivecomplete power controlling information, improving the reliability of theTPC command.

In accordance with an embodiment of the present invention, the PDCCH forindicating the TPC value includes: TPC commands of the PDCCHs schedulingPcells, TPC commands of the PDCCHs scheduling Scells when the Scells arescheduled with a cross-carrier; and TPC commands of the PDCCHsscheduling Scell with DAI values of more than 1, when the Scells arescheduled with a non cross-carrier.

Thus, when both of the cells in a downlink sub-frame send a powertransmitting command, if the UE does not detect PDCCH in one of thecells, the UE can still get the TPC value of the sub-frame from the TPCfield of the PDCCH in another cell. If only an Scell is currentlyscheduled by the Node B and the non cross-carrier scheduling method isused, as long as the Node B schedules at least 2 downlink datatransmissions on the Scell, the Node B can send a valid TPC command tothe UE, thereby avoiding degradation of uplink transmitting performancecaused by lack of an available TPC command for the UE.

As described above, the UE generates 2-bit information to be fed back byeach cell, and determines the corresponding ACK/NACK channel and theuplink power adjusting value. Thus, in step 105 the UE can send ACK/NACKinformation in the uplink direction with ACK/NACK informationtransmitting method based on the channel selection, and can set suitabletransmitting power according to the uplink power adjusting value. Themethod of FIG. 1 is not limited to the channel selection mapping tableused herein. For example, a mapping table like Table 1 or 2 may also beused.

FIG. 2 illustrates a TPC field in a PDCCH for scheduling an Scell fornon-cross carrier scheduling according to an embodiment of the presentinvention.

Referring to FIG. 2, as described in step 101 above, when an Scell isscheduled in a non cross-carrier manner, the TPC field in a PDCCHscheduling an Scell with a DAI of 1 is redefined as an ARI, while theTPC field in the PDCCH scheduling the Scell with a DAI greater than 1still carries a TPC command.

FIG. 3 is a flowchart illustrating eNB procedures for a TPCconfiguration according to an embodiment of the present invention.

Referring to FIG. 3, in step 301, the eNB determines if a PDCCH is forScell scheduling. When the PDCCH is not for Scell scheduling, i.e., itis for Pcell scheduling, then eNB configures the TPC field in the PDCCHas a TPC command in step 302.

However, when the PDCCH is for Scell scheduling, then eNB determines ifthe DAI of the PDCCH is equal to 1 in step 303. If the DAI of the PDCCHis not equal to 1, the eNB configures the TPC field in the PDCCH as aTPC command in step 302. However, the DAI of the PDCCH is equal to 1,the eNB configures the TPC field as an ARI in step 304.

In step 305, eNB configures the TPC field in the PDCCH, and then sendsthe PDCCH to the scheduled UE.

FIG. 4 is a flowchart illustrating UE procedures for TPC and UL resourceallocation according to an embodiment of the present invention.

Referring to FIG. 4, in step 401, UE checks if the decoded PDCCH is forScell scheduling. When the decoded PDCCH is not for Scell scheduling,i.e., it is for Pcell scheduling, the UE calculates the UpLink (UL)transmission power according to the bits in the TPC field of the PDCCHin step 402. However, when the decoded PDCCH is for Scell scheduling,the UE determines if the DAI of the PDCCH is equal to 1 in step 403.

When the DAI of the PDCCH is not equal to 1, the UE calculates the ULtransmission power according to the bits in the TPC field of the PDCCHin step 402. However, when the DAI of the PDCCH is equal to 1, in step404, the UE identifies the UL PUCCH resource according to the bitstransmitted in the TPC field of the PDCCH which is used for an ARI.

In step 405, the UE sends the PUCCH to eNB.

Although FIGS. 3 and 4 assume that the size of the bundling window M is2, 3 or 4, and that 2-bit DAI information can indicate uniquely thePDCCH sent by each Node B, these methods can also be used for M greaterthan 4, e.g., if TDD uplink and downlink configuration is 5, and thereis no other restriction, i.e., M is 9.

When an Scell is scheduled with a non cross-carrier, the TPC of a PDCCHscheduling an Scell with a DAI value of 1 is redefined as an ARI, andthe TPC of another PDCCH scheduling an Scell with a DAI value greaterthan 1 carries the TPC command. Here, in the bundling window, there canbe a plurality of PDCCHs scheduling Scell with DAIs of 1. Because inextreme cases, the UE may lose a PDCCH with a DAI of 1 sent by a certainNode B, and the UE cannot find the problem by DAI, in order to avoid thesituation that there is no ARI information for the UE, each of aplurality of TPC commands of PDCCHs scheduling Scell with their DAIs of1 sent in the bundling window are redefined as an ARI.

In order to reduce ACK/NACK resource overhead, the Node B can repeatedlysend the same ARI information on a plurality of PDCCHs for schedulingScell with DAIs of 1. Alternatively, the Node B can send different ARIinformation on the plurality of PDCCHs for scheduling Scell with DAIs of1, and a candidate channel should be defined when the plurality ofPDCCHs received by the UE indicate different ARIs, which schedule anScell and have DAIs of 1. For example, a channel indicated by an ARI ofa first PDCCH received by a UE, which schedules an Scell and is has aDAI of 1, can be defined as the candidate channel.

FIG. 5 is a block diagram illustrating a Node B apparatus for allocatingACK/NACK channel resources according to an embodiment of the presentinvention.

Referring to FIG. 5, a Node B apparatus includes a transmitter 500, asetting unit 510, and a receiver 520. Because an operation of allocatingACK/NACK channel resources by a Node B has been described with referenceto FIGS. 1 and 2 above, only a brief operation for each element will bedescribed below.

The setting unit 510 controls the UE to feedback ACK or NACK informationin a CA mode. Specifically, the setting unit 510 sets the TPC field ofthe PDCCH message to transmit ARI information, when a DAI value of aPDCCH message of a scheduled Scell in a non cross-carrier manner is 1,and the setting unit 510 sets the TPC field to transmit the TPC command,when the DAI value is greater than 1. The set PDCCH and downlink dataare transmitted to the UE through the transmitter 520. Thereafter,ACK/NACK feedback information for the downlink data is received throughthe receiver 520.

FIG. 6 is a block diagram illustrating a UE apparatus that usesallocated ACK/NACK channel resources according to an embodiment of thepresent invention.

Referring to FIG. 6, a UE apparatus includes a receiver 600, a generator610, and a transmitter 620. Because an operation of using allocatedACK/NACK channel resources by the UE has been described with referenceto FIG. 6 above, only a brief operation for each element will bedescribed hereinafter.

The receiver 600 receives downlink data and a PDCCH message transmittedfrom a Node B. The generator 610 generates ACK/NACK feedback informationfor each of the downlink data. Specifically, when the generator 610generates the ACK/NACK feedback information, the generator 610simultaneously determines two ACK/NACK channels corresponding to theScell according to the PDCCH message scheduling the Scell with a DAIvalue of 1, and determines transmitting power of the ACK/NACK feedbackinformation according to the PDCCH message scheduling the Scell with aDAI value of greater than 1, if the Scell is scheduled in a noncross-carrier manner. Thereafter, the ACK/NACK feedback information istransmitted using the determined ACK/NACK channels and transmittingpower through the transmitter 620.

While the present invention has been particularly shown and describedwith reference to certain embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims and theirequivalents.

What is claimed is:
 1. A method of allocating response channel resourcesby a Node B in a wireless communication system, the method comprising:setting a User Equipment (UE) to feed back Acknowledgement(ACK)/Negative Acknowledgement (NACK) information in a CarrierAggregation (CA) mode; setting a Transmit Power Control (TPC) field of aPhysical Downlink Controlling Channel (PDCCH) message to transmit anACK/NACK Resource Indicator (ARI) information, when a Downlink AssigningIndicator (DAI) value of the PDCCH message of a Secondary cell (Scell)scheduled in a non cross-carrier manner is 1; setting the TPC field totransmit a TPC command for the ACK/NACK feedback information, when theDAI value is greater than 1; and transmitting the PDCCH message anddownlink data to the UE.
 2. The method of claim 1, further comprising:setting a TPC field of a PDCCH message scheduling a Primary cell (Pcell)to transmit a TPC command; and transmitting the PDCCH message.
 3. Themethod of claim 1, further comprising: setting a TPC field of a PDCCHmessage of a Scell scheduled in a cross-carrier manner to transmit a TPCcommand; and transmitting the PDCCH message.
 4. The method of claim 1,wherein, when a size of a bundling window is greater than 4, ARIinformation transmitted in TPC fields of a plurality of PDCCH messagesfor scheduling the Scell with their DAI values of 1 are equal.
 5. Amethod of transmitting Acknowledgement (ACK)/Negative Acknowledgement(NACK) information using response channel resources by a User Equipment(UE) in a wireless communication system, the method comprising:receiving a Physical Downlink Controlling Channel (PDCCH) message anddownlink data from a Node B; generating ACK/NACK feedback informationfor the downlink data; determining an ACK/NACK channel corresponding toa Secondary cell (Scell) based on the PDCCH message scheduling the Scellwith a DAI value of 1, and determining a transmitting power of theACK/NACK feedback information based on the PDCCH message scheduling theScell with a DAI value of greater than 1, when the Scell is scheduled ina non cross-carrier manner; and transmitting the ACK/NACK feedbackinformation with the determined transmitting power using the determinedACK/NACK channel.
 6. A Node B for allocating response channel resourcesin a wireless communication system, the Node B comprising: a settingunit for setting a User Equipment (UE) to feed back Acknowledgement(ACK)/Negative Acknowledgement (NACK) information in a CarrierAggregation (CA) mode, setting a Transmit Power Control (TPC) field of aPhysical Downlink Controlling Channel (PDCCH) message to transmit anACK/NACK Resource Indicator (ARI) information, when a Downlink AssigningIndicator (DAI) value of the PDCCH message of a Secondary cell (Scell)scheduled in a non cross-carrier manner is 1, and setting the TPC fieldto transmit a TPC command for the ACK/NACK feedback information, whenthe DAI value is greater than 1; and a transmitter for transmitting thePDCCH message and downlink data to the UE.
 7. The Node B of claim 6,wherein the setting unit sets a TPC field of a PDCCH message schedulinga Primary cell (Pcell) to transmit a TPC command.
 8. The Node B of claim6, wherein the setting unit sets a TPC field of a PDCCH message of aScell scheduled in a cross-carrier manner to transmit a TPC command. 9.The Node B of claim 6, wherein, when a size of a bundling window isgreater than 4, ARI information transmitted in TPC fields of a pluralityof PDCCH messages for scheduling the Scell with their DAI values of 1being the same.
 10. A User Equipment (UE) for transmittingAcknowledgement (ACK)/Negative Acknowledgement (NACK) information usingresponse channel resources in a wireless communication system, the UEcomprising: a receiver for receiving a Physical Downlink ControllingChannel (PDCCH) message and downlink data from a Node B; a generator forgenerating ACK/NACK feedback information for the downlink data, anddetermining an ACK/NACK channel corresponding to a Secondary cell(Scell) based on the PDCCH message scheduling the Scell with a DAI valueof 1, and determining a transmitting power of the ACK/NACK feedbackinformation based on the PDCCH message scheduling the Scell with a DAIvalue of greater than 1, when the Scell is scheduled in a noncross-carrier manner; and a transmitter for transmitting the ACK/NACKfeedback information with the determined transmitting power using thedetermined ACK/NACK channel.